New York Representative Jerrold Nadler, a Democrat from New York, will introduce a bill that would repeal the federal Defense of Marriage Act (DOMA) without the support of Massachusetts Representative Barney Frank, the most powerful openly gay politician in Congress.

The bill, to be unveiled at a press event Tuesday, aims to repeal the 13 year old law that defines marriage as a heterosexual union for federal agencies and allows states to ignore gay marriages performed outside their borders.

But Frank, the nation's first representative to voluntarily come out of the closet, says he won't back the bill.

“It's not anything that's achievable in the near term,” Frank told gay weekly The Washington Blade.

“I think getting [the Employment Non-Discrimination Act], a repeal of 'don't ask, don't tell,' and full domestic partner benefits for federal employees will take up all of what we can do and maybe more in this Congress.”

Frank said he could not support the bill's “certainty provision.”

“The provision that says you can take your benefits as you travel, I think, will stir up unnecessary opposition with regard to the question of are you trying to export it to other states,” he said. “If we had a chance to pass that, it would be a different story, but I don't think it's a good idea to rekindle that debate when there's no chance of passage in the near term.”

Nadler, however, disagreed in a statement: “Our bill allows states to continue deciding those questions, while ensuring uniform access to critically important federal responsibilities and rights that hinge on marriage and upon which all married couples should be able to rely.”

Text of the legislation was not made available by Nadler's office, leaving open the question of how far the bill goes in attacking DOMA.